Augmented logarithmic spiral antenna structure applied to electromagnetic wave energy absorber, thermoelectric energy harvester, photoconductive antenna, array antenna and rectenna

Abstract

An augmented logarithmic spiral antenna structure includes a first conductive layer, a dielectric layer and a second conductive layer. The first conductive layer includes a first spiral arm and a plurality of second spiral arms. The first spiral arm includes a first initial radius. The second spiral arms are disposed around and connected to the first spiral arm, and each of the second spiral arms includes a second initial radius. The dielectric layer has a top surface and a bottom surface, and the top surface is connected to the first conductive layer. The second conductive layer is connected to the bottom surface. A plurality of the second initial radii of the second spiral arms are different from each other, and different from the first initial radius.

What is claimed is: 
     
       1. An augmented logarithmic spiral antenna structure, comprising:
 a first conductive layer, comprising:
 a first spiral arm comprising a first initial radius; and 
 a plurality of second spiral arms disposed around and connected to the first spiral arm, wherein each of the second spiral arms comprises a second initial radius; 
 
 a dielectric layer having a top surface and a bottom surface, and the top surface is connected to the first conductive layer; and 
 a second conductive layer connected to the bottom surface; 
 wherein a plurality of the second initial radii of the second spiral arms are different from each other, and different from the first initial radius. 
 
     
     
       2. The augmented logarithmic spiral antenna structure of  claim 1 , wherein the first spiral arm further comprises a first inner curve radius, a first outer curve radius, a flare rate, an angular position and a phase shift between two consecutive curves of the first spiral arm, and a plurality of following equations are satisfied: 
       
         
           
             
               
                 
                   r 
                   1 
                 
                 = 
                 
                   
                     r 
                     o 
                   
                   ⁢ 
                   
                     e 
                     
                       a 
                       ⁢ 
                       ∅ 
                     
                   
                 
               
               ; 
             
           
         
         
           
             
               
                 
                   r 
                   2 
                 
                 = 
                 
                   
                     r 
                     o 
                   
                   ⁢ 
                   
                     e 
                     
                       a 
                       ⁡ 
                       ( 
                       
                         ∅ 
                         + 
                         δ 
                       
                       ) 
                     
                   
                 
               
               ; 
             
           
         
         wherein r 0  is the first initial radius, r 1  is the first inner curve radius, r 2  is the first outer curve radius, a is the flare rate, ∅ is the angular position that varies from 0 to 3π, and δ is the phase shift. 
       
     
     
       3. The augmented logarithmic spiral antenna structure of  claim 2 , wherein a flare rate and an angular position of each of the second spiral arms are the same as the flare rate and the angular position of the first spiral arm. 
     
     
       4. The augmented logarithmic spiral antenna structure of  claim 1 , wherein both of the dielectric layer and the second conductive layer are a continuous layer, the first conductive layer is laminated on the top surface of the dielectric layer, and the bottom surface of the dielectric layer is laminated on the second conductive layer. 
     
     
       5. The augmented logarithmic spiral antenna structure of  claim 1 , wherein the first conductive layer consists of a lossy metal, the dielectric layer consists of a highly insulated material, and the second conductive layer consists of another lossy metal;
 wherein the lossy metal is nickel (Ni), the highly insulated material is SU-8 and has a relative permittivity of 2.8, and the another lossy metal is gold (Au). 
 
     
     
       6. The augmented logarithmic spiral antenna structure of  claim 1 , wherein a thickness of the first conductive layer is Z 1 , a thickness of the dielectric layer is Z 2 , a thickness of the second conductive layer is Z 3 , and the following condition is satisfied: 
       
         
           
             
               
                 Z 
                 1 
               
               = 
               
                 
                   Z 
                   3 
                 
                 < 
                 
                   
                     Z 
                     2 
                   
                   . 
                 
               
             
           
         
       
     
     
       7. The augmented logarithmic spiral antenna structure of  claim 6 , wherein the thickness of the first conductive layer is greater than a skin depth of the first conductive layer, the thickness of the dielectric layer is greater than a penetration depth of the dielectric layer, and the thickness of the second conductive layer is greater than a skin depth of the second conductive layer. 
     
     
       8. An electromagnetic wave energy absorber, comprising:
 a nanoantenna comprising at least one augmented logarithmic spiral antenna structure of  claim 1 , wherein the nanoantenna is configured to absorb an incident radiation, and a frequency of the incident radiation is f, and the following condition is satisfied: 
 
       
         
           
             
               
                 4.5 
                     
                 THz 
               
               < 
               f 
               ≤ 
               
                 100 
                 ⁢ 
                     
                 
                   THz 
                   . 
                 
               
             
           
         
       
     
     
       9. The electromagnetic wave energy absorber of  claim 8 , wherein the incident radiation is incident on the nanoantenna in a normal direction, and the nanoantenna has an average absorption corresponding to the incident radiation, the average absorption is AA, and the following condition is satisfied: 
       
         
           
             
               
                 88.5 
                 % 
               
               ≤ 
               
                 AA 
                 . 
               
             
           
         
       
     
     
       10. An augmented logarithmic spiral antenna structure, comprising:
 a first conductive layer having a first pattern, and comprising:
 a first spiral arm comprising a first initial radius; and 
 a plurality of second spiral arms disposed around and connected to the first spiral arm, wherein each of the second spiral arms comprises a second initial radius; 
 
 a dielectric layer connected to the first conductive layer and having a second pattern, wherein the second pattern is the same as the first pattern; and 
 a second conductive layer connected to the dielectric layer, wherein the dielectric layer is located between the first conductive layer and the second conductive layer; 
 wherein a plurality of the second initial radii of the second spiral arms are different from each other, and different from the first initial radius. 
 
     
     
       11. The augmented logarithmic spiral antenna structure of  claim 10 , wherein the first spiral arm further comprises a first inner curve radius, a first outer curve radius, a flare rate, an angular position and a phase shift between two consecutive curves of the first spiral arm, and a plurality of following equations are satisfied: 
       
         
           
             
               
                 
                   r 
                   1 
                 
                 = 
                 
                   
                     r 
                     o 
                   
                   ⁢ 
                   
                     e 
                     
                       a 
                       ⁢ 
                       ∅ 
                     
                   
                 
               
               ; 
             
           
         
         
           
             
               
                 
                   r 
                   2 
                 
                 = 
                 
                   
                     r 
                     o 
                   
                   ⁢ 
                   
                     e 
                     
                       a 
                       ⁡ 
                       ( 
                       
                         ∅ 
                         + 
                         δ 
                       
                       ) 
                     
                   
                 
               
               ; 
             
           
         
         wherein r 0  is the first initial radius, r 1  is the first inner curve radius, r 2  is the first outer curve radius, a is the flare rate, ∅ is the angular position that varies from 0 to 3π, and δ is the phase shift. 
       
     
     
       12. The augmented logarithmic spiral antenna structure of  claim 11 , wherein a flare rate and an angular position of each of the second spiral arms are the same as the flare rate and the angular position of the first spiral arm. 
     
     
       13. The augmented logarithmic spiral antenna structure of  claim 10 , wherein the second conductive layer is a continuous layer having a surface, the first conductive layer is laminated on the dielectric layer, the first pattern is aligned with the second pattern, and the dielectric layer is laminated on the surface of the second conductive layer. 
     
     
       14. The augmented logarithmic spiral antenna structure of  claim 10 , wherein the first conductive layer consists of a lossy metal, the dielectric layer consists of a highly insulated material, and the second conductive layer consists of another lossy metal;
 wherein the lossy metal is nickel (Ni), the highly insulated material is SU-8 and has a relative permittivity of 2.8, and the another lossy metal is gold (Au). 
 
     
     
       15. The augmented logarithmic spiral antenna structure of  claim 10 , wherein a thickness of the first conductive layer is Z 1 , a thickness of the dielectric layer is Z 2 , a thickness of the second conductive layer is Z 3 , and the following condition is satisfied: 
       
         
           
             
               
                 Z 
                 1 
               
               = 
               
                 
                   Z 
                   3 
                 
                 < 
                 
                   
                     Z 
                     2 
                   
                   . 
                 
               
             
           
         
       
     
     
       16. The augmented logarithmic spiral antenna structure of  claim 15 , wherein the thickness of the first conductive layer is greater than a skin depth of the first conductive layer, the thickness of the dielectric layer is greater than a penetration depth of the dielectric layer, and the thickness of the second conductive layer is greater than a skin depth of the second conductive layer. 
     
     
       17. An electromagnetic wave energy absorber, comprising:
 a nanoantenna comprising at least one augmented logarithmic spiral antenna structure of  claim 10 , wherein the nanoantenna is configured to absorb an incident radiation, and a frequency of the incident radiation is f, and the following condition is satisfied: 
 
       
         
           
             
               
                 4.5 
                     
                 THz 
               
               < 
               f 
               ≤ 
               
                 100 
                 ⁢ 
                     
                 
                   THz 
                   . 
                 
               
             
           
         
       
     
     
       18. The electromagnetic wave energy absorber of  claim 17 , wherein the incident radiation is incident on the nanoantenna in a normal direction, and the nanoantenna has an average absorption corresponding to the incident radiation, the average absorption is AA, and the following condition is satisfied: 
       
         
           
             
               
                 88.5 
                 % 
               
               ≤ 
               
                 AA 
                 . 
               
             
           
         
       
     
     
       19. A photoconductive antenna, which is configured to replace one of a spiral antenna and a bow tie antenna, and the photoconductive antenna comprising:
 the first conductive layer of the augmented logarithmic spiral antenna structure of  claim 10 ; 
 a photo-absorbing semiconductor layer connected to the first conductive layer, wherein a structure of the photo-absorbing semiconductor layer is the same as a structure of the dielectric layer of the augmented logarithmic spiral antenna structure of  claim 10 ; and 
 the second conductive layer of the augmented logarithmic spiral antenna structure of  claim 10  connected to the photo-absorbing semiconductor layer, wherein the photo-absorbing semiconductor layer is located between the first conductive layer and the second conductive layer. 
 
     
     
       20. An array antenna, comprising:
 a plurality of the augmented logarithmic spiral antenna structures of  claim 10 , wherein a plurality of the first conductive layers of the augmented logarithmic spiral antenna structures are arranged at intervals, a plurality of the dielectric layers of the augmented logarithmic spiral antenna structures are arranged at intervals, and a plurality of the second conductive layers of the augmented logarithmic spiral antenna structure are connected to each other or formed integrally. 
 
     
     
       21. The array antenna of  claim 20 , wherein a slot is located between each two of the augmented logarithmic spiral antenna structures and has a width, a plurality of the slots are connected to each other in a grillage type, and the width of each of the slots is the same. 
     
     
       22. A rectenna, which is used for a communication or an energy harvesting device, and the rectenna comprising:
 the augmented logarithmic spiral antenna structure of  claim 10  receiving a radio frequency signal or a radiation; and 
 a rectifier module electrically connected to the augmented logarithmic spiral antenna structure and converting the radio frequency signal or the radiation from an alternating current into a direct current.